The railway industry has always lagged the mobile industry in adopting the latest communications technologies. This is attributed mainly to the specific technology challenges arising in the context of mobility scenarios, specially at high speeds and structural factors relating to the development cycles mismatch with mobility original equipment manufacturers having much longer development cycles. This has resulted in a technology landscape which is fragmented, complex and costly for Original Equipment Manufacturers (OEMs) and operators yet still falls short of passengers rising expectations and demand for data driven services. However, the convergence of rapid developments of extensively researched and developed technologies in wireless communication such as 5G, sensor technology and Internet of Things (IoT) paradigms show potential to serve multiple previously siloed requirements of different applications in a more efficient manner. In this paper we address the deficit in realistic channel models for high speed Train-Onboard communication. We conduct measurements to evaluate the Channel Impulse Response (CIR) on a German high-speed track under real operating conditions in a rural overland environment at speeds up to 300 km/h. The Coherence Bandwidth, and Root Mean Square (RMS) delay are measured at 2.7 GHz and 5.6 GHz. Our measurements indicate that the coherence bandwidth can vary significantly even in very similar train environments. This calls for further investigation to establish the ranges of useful bandwidth for onboard communication applications.
